diff --git a/esp32/include/ControllerConfiguration.h b/esp32/include/ControllerConfiguration.h
index bd9e24f..f6e300f 100644
--- a/esp32/include/ControllerConfiguration.h
+++ b/esp32/include/ControllerConfiguration.h
@@ -102,10 +102,12 @@
 #define ESP_STALE_TIMEOUT           (MQTT_TIMEOUT+(700*1000))
 
 #define MAX_PLANTS          7
-#define SOLAR_CHARGE_MIN_VOLTAGE 7  /**< Sun is rising (morning detected) */
-#define SOLAR_CHARGE_MAX_VOLTAGE 9  /**< Sun is shining (noon)  */
-#define SOLAR_MAX_VOLTAGE_POSSIBLE 100  /**< higher values are treated as not connected sensor  */
+#define SOLAR_CHARGE_MIN_VOLTAGE    7   /**< Sun is rising (morning detected) */
+#define SOLAR_CHARGE_MAX_VOLTAGE    9   /**< Sun is shining (noon)  */
+#define SOLAR_MAX_VOLTAGE_POSSIBLE  100 /**< higher values are treated as not connected sensor  */
 #define VOLT_MAX_BATT               4.2f
+#define VOLT_MIN_BATT               3.0f    /**< Minimum battery voltage for normal operation */
+#define LOWVOLT_SLEEP_FACTOR        3       /**< Factor for nightsleep delay, if the battery drops below minimum (@see VOLT_MIN_BATT) */
 
 #define MAX_CONFIG_SETTING_ITEMS 100 /**< Parameter, that can be configured in Homie */
 #define MAX_JSON_CONFIG_FILE_SIZE_CUSTOM 2500
diff --git a/esp32/include/LogDefines.h b/esp32/include/LogDefines.h
index c400a6b..78285f5 100644
--- a/esp32/include/LogDefines.h
+++ b/esp32/include/LogDefines.h
@@ -39,6 +39,7 @@
 #define LOG_DEBUG_CODE 1001
 #define LOG_SLEEP_NIGHT 100
 #define LOG_SLEEP_DAY 101
+#define LOG_SLEEP_LOWVOLTAGE 502
 #define LOG_SLEEP_CYCLE 102
 #define LOG_MISSING_PUMP -4
 #define LOG_BOOT_ERROR_DETECTION 10000
diff --git a/esp32/include/PlantCtrl.h b/esp32/include/PlantCtrl.h
index cae0ccf..1067308 100644
--- a/esp32/include/PlantCtrl.h
+++ b/esp32/include/PlantCtrl.h
@@ -148,7 +148,7 @@ public:
             {
                 return MISSING_SENSOR;
             }
-            if (mMoisture_raw.getMedian() > MOIST_SENSOR_MAX_FRQ)
+            else if (mMoisture_raw.getMedian() > MOIST_SENSOR_MAX_FRQ)
             {
                 return SHORT_CIRCUIT_MODE;
             }
diff --git a/esp32/src/main.cpp b/esp32/src/main.cpp
index 6a3a4b1..db64b10 100644
--- a/esp32/src/main.cpp
+++ b/esp32/src/main.cpp
@@ -80,6 +80,7 @@ long nextBlink = 0; /**< Time needed in main loop to support expected blink code
 
 RunningMedian waterRawSensor = RunningMedian(5);
 float mSolarVoltage = 0.0f; /**< Voltage from solar panels */
+float mBatteryVoltage = 0.0f; /**< Voltage from lipo */
 unsigned long setupFinishedTimestamp;
 
 bool pumpStarted = false;
@@ -189,7 +190,12 @@ void espDeepSleep(bool afterPump = false)
   }
   else
   {
-    if (mSolarVoltage < SOLAR_CHARGE_MIN_VOLTAGE)
+    if (mBatteryVoltage < VOLT_MIN_BATT) 
+    {
+      log(LOG_LEVEL_INFO, String(String(mBatteryVoltage) + "V! Almost empty -> deepSleepNight times " + String(LOWVOLT_SLEEP_FACTOR)), LOG_SLEEP_LOWVOLTAGE);
+      secondsToSleep = (deepSleepNightTime.get() * LOWVOLT_SLEEP_FACTOR);
+    }
+    else if (mSolarVoltage < SOLAR_CHARGE_MIN_VOLTAGE)
     {
       log(LOG_LEVEL_INFO, String(String(mSolarVoltage) + "V! Low light -> deepSleepNight"), LOG_SLEEP_NIGHT);
       secondsToSleep = deepSleepNightTime.get();
@@ -1042,7 +1048,7 @@ void plantcontrol()
 
   Serial << "W : " << waterRawSensor.getAverage() << " mm (" << String(waterLevelMax.get() - waterRawSensor.getAverage()) << " mm left)" << endl;
 
-  float batteryVoltage = battery.getVoltage(BATTSENSOR_INDEX_BATTERY);
+  mBatteryVoltage = battery.getVoltage(BATTSENSOR_INDEX_BATTERY);
   float chipTemp = battery.getTemperature();
   Serial << "Chip Temperatur " << chipTemp << " °C " << endl;
 
@@ -1062,8 +1068,8 @@ void plantcontrol()
         sensorWater.setProperty("distance").send(String(waterRawSensor.getAverage()));
       }
     }
-    sensorLipo.setProperty("percent").send(String(100 * batteryVoltage / VOLT_MAX_BATT));
-    sensorLipo.setProperty("volt").send(String(batteryVoltage));
+    sensorLipo.setProperty("percent").send(String(100 * mBatteryVoltage / VOLT_MAX_BATT));
+    sensorLipo.setProperty("volt").send(String(mBatteryVoltage));
     sensorLipo.setProperty("current").send(String(battery.getCurrent()));
     sensorLipo.setProperty("Ah").send(String(battery.getAh()));
     sensorLipo.setProperty("ICA").send(String(battery.getICA()));
@@ -1082,7 +1088,7 @@ void plantcontrol()
     Serial.flush();
   }
 
-bool isLowLight = mSolarVoltage <= 9;
+bool isLowLight = (mSolarVoltage <= SOLAR_CHARGE_MAX_VOLTAGE);
 #if defined(TIMED_LIGHT_PIN)
   
   bool shouldLight = determineTimedLightState(isLowLight);